Description: The campanula genus, which comprises more than 300 annuals, perennials and biennials, has become one of the most popular and identifiable genera in the United States. The plants vary greatly in habit, being either clump-forming, spreading and trailing or tall and erect. Their flowers range from star-shaped to bell-shaped to tubular. I have chosen two of my favorite species, which are less common, because each has its irresistible charms.

Campanula punctata is a clump-forming perennial with creeping rhizomes and rosettes of light green, toothed leaves. The flowers are the real prize -- 2-inch-long pale rose bell- to tubular-shaped flowers. Their insides look as if a baker sprayed them with red confectioners' sugar. Delightful! Better yet, in the Bay Area, the flowers bloom from spring through late fall.

Campanula incurva is a bit of a rarity, but worth finding. Like its more famous cousin, 'Canterbury Bells,' it's a biennial, meaning you'll need to wait an extra year for the flowers. In the meantime, it produces a rosette of lovely, dark green elliptic leaves. And when it does flower -- wow! One is treated to an abundance of large, icy-blue bell-shaped flowers unlike those of any other species in this family.

Cultivation: Grow in fertile, moist, well-drained neutral to alkaline soil in sun or some shade. Protect from scorching sun. C. punctata will thrive in fertile, sandy loam. Punctata is a 2- to 3-foot-high stand-alone species and will gradually fill out an area, so give it some space. Keep in a pot if containment is preferred. Rhizomes can be divided, so share this delightful species with others.

Incurva, conversely, is of a spreading habitat, not reaching more than 18 inches tall under most circumstances. Since it is monocarpic and does not freely self-seed, one need not worry about it taking over a patch of your garden.

Pests: Slugs, snails, spider mites and aphids can be problems. Susceptible to powdery mildew. With proper drainage and an open habitat, many of the dangers can be minimized.

Comments: Though the most common variety of C. punctata is aptly known as 'Cherry Bells,' there is quite a range of color in these nodding, tubular flowers. The exteriors range in color from the palest milky rose to a bright cherry red, with the bottoms usually dusted white and the slightly hairy interiors speckled with pink, cherry or bright red dots.

The species is native to Asia, where it grows under trees on forested hillsides. In Japan, it is called hotarubukuro, roughly translated as "bag with fireflies inside," which charmingly characterizes this hardy perennial. Given its attractive basal leaves and architectural upright habit, which allows the long-lasting flowers to dangle naturally, it's no wonder this species has become a star in the campanula universe.

Where one's reaction to a stand of rosy punctata bells is likely to be joy, seeing C. incurva for the first time is likely to elicit wonder. There's just no way to adequately describe the sight of these large white bells, frosted with the palest or deepest lilac, with this range of color apparent on single plants. Even the buds are fascinating, looking like, as Annie's Annuals describes them, "rosy-tipped, Turkish turbans." Adding to their distinctive look, the very tips of the bells curl back ever so slightly, giving them a sort of fluted appearance. Perhaps this "lip" makes them more inviting to hummingbirds, which seem to especially love the bell and tubular campanula species.

Whichever your choice, these two unique campanulas will be the talk of your garden.

Favorite plant?

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